1 December 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a group of semi-parallel ridges--yardangs--etched by wind into layered sedimentary rock on the floor of an unnamed crater in Terra Cimmeria. Many craters on Mars have been the sites of sedimentation. Over time, these sediments have become lithified. This picture is located near 31.3S, 214.6W. The image covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the left/upper left.